Earthing kettle element

[Barge]

I asked this question in a different thread and thought I should probably just start a new one to avoid getting OT on the other thread.

Firstly, I understand the importance of earthing electrical equipment and having all work carried out and signed off by a licensed electrician.

My query relates to earthing the big w/ k-mart kettle elements if I'm still using the IEC cord that they come with. I don't see why the kettle should necessarily be earthed (other than for being extra cautious) when the element is earthed through the cable. If the weld less elements from CB, etc don't need to be earthed, then why should these be? If I have them in an enclosure that is sealed, shouldn't that be enough?

Cheers

 

[takai]

Weldless elements are earthed, just through the housing and pot not the element itself.

 

[Barge]

But the kettle still isn't earthed. I don't get the difference.

 

[takai]

The kettle is earthed on a weldless setup, just through the element housing and therefore the whole kettle itself.

 

[Barge]

So when you screw the element on there is metal on metal contact between the element and the kettle?

 

[QldKev]

Hopefully, but in the real world not always. A lot of people do put seals on both sides of the pot to element contact areas, hence removing this contact path. If the element was off centre allowing the thread to touch the pot then that could work. When you have water in the pot that would create a path from the element housing to the pot for the earth. But boil dry and they may not have a decent earth path? But scary now we think of it.

 

[TheWiggman]

It's important to think what the earth is actually there for. It's possible for a conductive part of an appliance to be touched by the active if there was an internal cable fault, which would make the whole thing 'live'. If a person touched it they would become the new neutral, and current would flow through them to the ground. If the appliance was earthed, the earth closes the loop and takes out the fuse/CB before anyone gets a chance to touch it. In the days before earth leakage detection, if this didn't happen the human would be zapped until the fuse blew.
If the element and pot are insulated from one another, that's the problem*. If a cable came off inside the junction box and touched the pot, the pot would become live and there's a chance of getting zapped. Though your electrician would have told you this when he/she wired it up

*ed: IF the junction box/cover can touch the pot

 

[Barge]

I was also wondering how your setup is wired Kev.

From one of your vids it looks like the enclosure is earthed. Is it in direct contact with the kettle as well?

 

[trevgale]

Barge, I assume you are talking about the elements from the $8 jugs. from memory they have a silicone gasket that would go against the kettle and 3 screws that connect the element (inside of jug) to the plastic section that the cord plugs into (outside of jug). With this arrangement there is no transfer of earth to the pot as it was designed to go into a plastic jug where earthing is not required.

You could drill a hole above water level and install a bolt with a nut and star washer to connect the earth to, wouldn't be real pretty though.

 

[Barge]

[quote name="TheWiggman" If a cable came off inside the junction box and touched the pot, the pot would become live and there's a chance of getting zapped. [/quote]

That's what I'm talking about. How can a wire come loose if I use the iec cable and connectors as is. That is, not cutting the connectors off and wiring direct to the element.

 

[Barge]

You could drill a hole above water level and install a bolt with a nut and star washer to connect the earth to, wouldn't be real pretty though.

That's what I was thinking but wasn't sure if it is necessary if the original connector is used without modification.

 

[Camo6]

An earthing system is only as good as its connections. If it's easier for electricity to go through your body than through any high resistance connections it will.

Most kettle element seals I've used seal both sides of the pot like a grommet therefore insulating themselves from the metal pot. If you had a loose connection/short/arc to the pot then it'd become a live conductor.

 

[rude]

In other words if the pot becomes alive it is just waiting to kill you

 

[real_beer]

I don't see why the kettle should necessarily be earthed (other than for being extra cautious) when the element is earthed through the cable. If the weld less elements from CB, etc don't need to be earthed, then why should these be? If I have them in an enclosure that is sealed, shouldn't that be enough?

Cheers

Because if someone other than yourself ever used it and didn't know they had to use the IEC cord with it, and the home they used it in didn't have one in the meter box, you'd be responsible for killing them if things went pear shaped.
Luckily you understand that a licensed electrician would be signing it off so you'd be okay because he wouldn't approve it.

 

[Barge]

I get all that. What i don't get is how the pot could become live. There are no wires as the IEC plug is going into the element end directly, just like the weld free setup. And it couldn't be used without that cord. So I still don't get the reasoning, other than "if you don't you might die".

Don't get me wrong, that's the reason (and the sparky won't have it any other way) I will have it earthed. I just can't see how that setup can cause a leakage.

 

[takai]

There are many ways it can become live, the one that i have seen a couple of times is that the plastic surrounding the IEC pins gets soft and squidgy from all the current passing through the pin and eventually fails and shorts through to the pot. Both times this has blown the fuse because the melted pin also let water into the ground recess thereby bridging the circuit. But if it doesnt happen (and it is random remember) then bzzzt.

The kettle elements are designed for use with plastic housings, where the chance of coming in contact with anything electrically conductive is minimal.

 

[Barge]

Fair enough. What about using the weld free element with o-rings. That would insulate the pot, too? I'm thinking they would be easier but I'm worried they're not as safe.

 

[real_beer]

I get all that. What i don't get is how the pot could become live. There are no wires as the IEC plug is going into the element end directly, just like the weld free setup. And it couldn't be used without that cord. So I still don't get the reasoning, other than "if you don't you might die".

Don't get me wrong, that's the reason (and the sparky won't have it any other way) I will have it earthed. I just can't see how that setup can cause a leakage.

I don't know what I was thinking about when I first read your question and went off on another tangent. If the element is earthed through the cable it will be okay, I've done it myself a few years ago. :icon_cheers:

That's what they're designed for so you don't have too worry about wiring them up yourself.

http://www.ebay.com.au/itm/like/221816416250?limghlpsr=true&hlpht=true&ul_noapp=true&hlpv=2&chn=ps&lpid=107&ops=true&viphx=1
http://www.craftbrewer.com.au/shop/details.asp?PID=3853

 

[takai]

You only need one O-ring to seal the element. Put it on the inside with a recessed 1" nut.

 

[Camo6]

A weldless element makes contact via the lock nut but an additional earth wouldn't hurt.

In a perfect world we wouldn't need an earth system. It doesn't serve any purpose in an electrical circuit other than protecting life. Unfortunately, due to some prick Murphy and his messed up laws, shit happens.

Say you had a seal leak a trail of water over your active and down the plastic separator to the pot wall. As the seal has insulated the element from the pot (containing lovely pure de-ionised water) the pot becomes live. It's sitting on a wooden bench so there's no path to ground and it's happy sitting there full of potential difference.

Would you be comfortable relying on an RCD to save you if you touched it? Forget fuses and circuit breakers, there only concerned about not setting the house on fire. An RCD measures earth leakage by comparing the incoming current with the outgoing current. It will only fault if some of this current goes to ground. If there's no path to ground it's happy for you to light up like a Christmas tree as long as you give back what you take.

I don't know why the OP is so adamant on this subject. If you can put a 40mm hole in a pot and stop it from leaking how hard is it to seal a 5mm hole?

There's a reason these regulations are mandatory and, believe it or not, the main one is "because you might die."